In the operation of oil well tools, it is necessary to actuate the tool at a desired location downhole. Various systems for actuating the tools have been used. One system uses an electric line cable to transmit control signals which actuate the downhole tool to receive data from the tool. Electric line well intervention can be costly, requires special tools and trained personnel, and can cause rig delays. Offshore, space for electric line equipment could be a problem since equipment for other procedures scheduled before or after running the tool may already occupy what little space is available.
Another system uses established profiles in the well to set and actuate the tools. However such systems are only useful when profiles are present in the completed well. In such systems the tool becomes supported by the recessed profile with the resulting weight shift actuating the tool. These systems are subject to inexact actuation when the tool encounters restrictive passages downhole and exhibits the same conditions as being suspended in the profiles.
A third system uses a pressure sensor to actuate the tool when the pressure downhole exceeds a predetermined level. Such systems are subject to inexact actuation due to deviations in downhole temperature and pressure conditions and sensitivities of known pressure transducers.
A fourth system uses an accelerometer with a time delay, actuating the tool when no motion has been detected for a predetermined period. Such systems are obviously subject to premature actuation if the tool becomes lodged downhole.
It is the object of the present invention to actuate downhole tools and to transmit collected data uphole using only a nonconducting cable. The present invention allows control over and communication with downhole tools using readily available rig equipment and personnel.